Large urban jails provide an opportunity for intervention for HIV. Among people with HIV, 25% enter jails each year. Estimates of the rate of substance abuse for people in jail are in the 70% to 80% range. The jail is a focal point for people with HIV and for people at risk for HIV, as well as other health conditions. Time is jail is universally shared experience of disempowerment among people involved in the criminal justice system. To capitalize on jail as an opportunity for HIV prevention intervention, this project examines the effectiveness of an empowerment based education and mutual support intervention for people with substance abuse problems leaving jail. Through a combination of in- reach and engagement in the jail and continued outreach and intervention outside the jail, the intervention TEACH Inside TEACH Outside (TITO) delivers 4 key messages to its participants: you can live a healthy life, services are available to support you, activist work has put this in place, and you can be an activist for yourself and your community. This study proposes an integrated dialogue between randomized controlled trial methods and ethnographic research methods to assess the effectiveness of TITO against an control condition receiving an infection prevention and safety intervention. 400 individuals will be recruited and randomized to the 2 conditions in jail and followed by survey and qualitative researchers for one year after jail release. The primary outcomes are reduced HIV risk behavior and reduced likelihood of jail reincarceration. PUBLIC HEALTH RELEVANCE: The jail is a focal point for people with HIV and for people at risk for HIV, as well as other health conditions. Time is jail is universally shared experience of disempowerment among people involved in the criminal justice system. To capitalize on jail as an opportunity for HIV prevention intervention, this project examines the effectiveness of an empowerment based education and mutual support intervention for people with substance abuse problems leaving jail. The primary outcomes are reduced HIV risk behavior and reduced likelihood of jail reincarceration.